Two research projects are proposed. (1) Correlative studies on the structure and function of the inner ear. The otolithic organs and/or the cristae ampullares will be individually and selectively destroyed in cats, pigeons, rabbits and monkeys. The spontaneous and experimentally induced animal behavior will be examined serially during the course of recovery. The temporal bones of these animals will be histologically examined to confirm the lesions of the inner ear. (2) Histopathological study of the temporal bones of experimental animals and humans will be performed by the celloidin embedding technique. The temporal bones will be taken from patients with clinically well studied and documented disease entities, the pathologies of which still remain obscure. Special interest will be paid to the study of inner ear vertigo, otosclerosis and heavy metal intoxication. In both animal and human specimens, scanning and transmission electron microscopes will be utilized for the observation of auditory and equilibrial sensory epithelia.